Include member email in form submission

I have a form that only members can access that consists of two Text Areas. I'd like to automatically have the member's email address included as part of the form submission. This doesn't appear to be the default behaviour when the data is exported to Google Drive and none of the form submissions are appearing in Contacts > Form Submitters.

Website: https://www.scriptshifters.com/basic-script-shift

I think these other topics in the forum are asking for the same thing:
 

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